Famine is both a risk and quite possibly present in at least some areas of the northern Gaza Strip, a senior U.S. State Department official said on Friday, while adding that a scarcity of trucks was an obstacle to getting more aid into the densely populated enclave under Israel siege.

"While we can say with confidence that famine is a significant risk in the south and center but not present, in the north, it is both a risk and quite possibly is present in at least some areas," the official told Reuters on the condition of anonymity.

Earlier this month a global authority on food security - backed by the United Nations - warned that famine was imminent and likely to occur by May in northern Gaza and could spread across the enclave by July.

Malnutrition and food insecurity have probably exceeded famine levels in Gaza's north, and hunger-linked death rates were likely to do so soon, said the report by the Integrated Food Security Phase Classification.

The number of trucks distributing aid in south and central Gaza had nearly topped 200 a day, an increase compared to a month ago, but more were needed, the State Department official said.

"You need to address the full nutrition needs of the population of Gaza of all ages. That means more than just that minimal survival level feeding," the official said, adding that malnutrition, infant newborn and young child mortality was a significant problem that was growing.

"It has to be addressed by additional assistance coming and the right kind of assistance coming in," he said.